Amaury (or Amalric) participated in the Albigensian Crusade under his father's command. He inherited the County of Toulouse (that his father had taken from Raymond VI of Toulouse as a reward for his role in the Crusade) when his father died, he had to give up the territory to King Louis VIII in 1224. In 1230 Amaury became Constable of France, an office previously held by his uncle Mathieu II of Montmorency. In 1239 he participated in the Crusade of 1239 and was taken prisoner after the defeat at Gaza. He was imprisoned in Cairo and was freed in 1241, but died in Otranto that same year while on the journey home.